1. Field of the Invention
The present invention relates to automotive lamps to be mounted in automotive vehicles. In particular, the present invention relates to an automotive lamp unit and a method for manufacturing the same, in which bus bars are integrated with a resin base member (hereinafter referred to as a base member) and lamps, such as passenger compartment lamps, map lamps, vanity-mirror lamps, door lamps, and trunk compartment lamps, are mounted on the bus bars.
2. Description of the Related Art
An automotive lamp unit, in which a room lamp and a map lamp are mounted on one base member and are individually switched on and off by a switch unit, is disclosed in, for example, Japanese Patent Application No. 11-161944 applied by an applicant the same as the assignee of the present application.
The configuration of the automotive lamp unit disclosed in the above-described application is described below with reference to FIGS. 10 to 14.
In FIGS. 10 to 12, a bus bar 2 is formed integrally with a base member 1 by molding, symmetrical with respect to a longitudinally intermediate part of the base member 1 (see FIG. 13). Push switches (hereinafter referred to as switches) 3 and 4 are disposed so that protrusions 3a and 4a of the switches 3 and 4, respectively, are disposed at the rear sides of lenses 7 and 8 (described below), respectively, the switches 3 and 4 being connected to terminals 2a and 2b, respectively. Lamps 5 and 6 are resiliently supported by raised tabs 2c and 2d, respectively, of the bus bar 2.
Terminals 2e are connector terminals connecting to an in-vehicle battery, to a door switch for switching on-and-off by opening-and-closing of a door, and to the ground. A lamp lighting circuit including the bus bar 2, the switches 3 and 4, and the lamps 5 and 6 is shown in FIG. 14, the operation of the circuit being described below.
A pair of the lenses 7 and 8 are formed in a size sufficient to cover the front side of the base member 1. Bearings 7a and 8a are formed at the longitudinal sides of each lens 7 or 8 at a longitudinally intermediate part of the base member 1 for rotatably supporting shafts 1aand 1b protruding from the longitudinal sides of the base member 1 at longitudinally intermediate parts thereof.
Anchoring parts 7b and 8b including hooks 7b1 and 8b1, respectively, are movably provided at the sides of the lenses 7 and 8, respectively, toward the ends thereof, so that the hooks 7b1 and 8b1 do not remove from fixing shafts 1c and 1d, respectively.
The lenses 7 and 8 are provided with projections 7c and 8c, respectively, at the rear sides thereof, opposing the protrusions 3a and 4a of the switches 3 and 4, respectively. The lenses 7 and 8 are supported at the projections 7c and 8c, respectively, in a manner such that the anchoring parts 7b and 8b are pressed upwardly by a resilient force applied to the protrusions 3a and 4a, respectively, with the lenses 7 and 8 pivoting on the bearings 7a and 8a, respectively.
A gap G is formed between the lenses 7 and 8 so that the lenses 7 and 8 can pivot. The lamp unit is provided with screw-passing holes 1e therein for fixing the lamp unit to the ceiling at the front side thereof.
The lamp lighting circuit shown in FIG. 14 is described below.
The terminals 2a and 2b shown in FIG. 12 are connected to the switches 3 and 4. When the protrusions 3a and 4a of the respective switches 3 and 4 are not pressed, contact points 3b1 and 4b1 and contact points 3b2 and 4b2 are connected, respectively, to each other via a contact plate which is movable by being pressed by the protrusions 3a and 4a, and when the protrusions 3a and 4a of the switches 3 and 4, respectively, are pressed, the contact points 3b1 and 4b1 are connected to contact points 3b3 and 4b3, respectively, to each other via the contact plate.
A terminal 2e1 included in the terminals 2e is grounded via a door switch 9 which is put on when a door is open. A terminal 2e2 is connected to the positive pole of an in-vehicle battery 10. A terminal 2e3 is grounded.
The operation of the circuit is described below. When the protrusions 3a and 4a of the respective switches 3 and 4 are not pressed, as shown in FIG. 14, and the door is open, thereby closing the door switch 9, the current from the positive pole of the battery 10 flows so as to split into two flows through lamps 5 and 6, the flows passing to the ground via switches 3 and 4, respectively, and the door switch 9, thereby turning on the lamps 5 and 6 and illuminating the compartment.
When the door is closed, thereby opening the door switch 9, and an end of the lens 7 of the driver""s seat side is pressed, thereby pressing the protrusion 3a of the switch 3, the contact point 3b1 comes into contact with the contact point 3b3, whereby the current from the positive pole of the battery 10 flows to the ground through the lamp 5 and the switch 3, thereby switching on the lamp 5 so as to be used as a map lamp of the driver""s seat side.
Regardless of whether the switch 3 is put on or put off, the contact point 4b1 comes into contact with the contact point 4b3 when an end of the lens 8 of the passenger""s seat side is pressed, thereby pressing the protrusion 4a of the switch 4, whereby the current from the positive pole of the battery 10 flows to the ground through the lamp 6 and the switch 4, thereby switching on the lamp 6 so as to be used as a map lamp of the passenger""s seat side.
In the automotive lamp unit in which the lamps are switched on and off as described above, six bus bars 2 are required, as shown in FIG. 13. When the bus bars 2 are disposed in the lamp unit, the six bus bars 2 must be manually placed in an injection mold. Therefore, a problem occurs in that the preparation for molding is laborious.
Another problem is that the bus bars 2 set in the injection mold move in the mold while injecting a resin, thereby producing defective products.
In order to overcome these problems, a technology disclosed in, for example, Japanese Unexamined Patent Application Publication No. 7-323784, may be used, in which a plurality of the above-described bus bars are connected with each other via bridge portions so as to form one integral bus bar unit. The bus bar unit is set in an injection mold, and is integrated with the base member by an injection molding.
In the subsequent process, the bridge portions are cut by using a press or the like, thereby electrically dividing the bus bar unit into a plurality of bus bars. However in this method, two processes, namely, an injection-molding process and a cutting process of the bridge portions, are required, and a blanking die is necessary, whereby the manufacturing cost is increased. Moreover, metallic particles of the cut bridge-portions must be disposed of as wastes.
Accordingly, it is an object of the present invention to provide an automotive lamp unit and a method for manufacturing the same, in which one integral bus bar unit including a plurality of bus bars connected at bridge portions is placed in an injection mold and the plurality of bus bars are separated from each other at the bridge portions without cutting away the bridge portions, then a resin is injected into the injection mold, thereby forming a product. The product can be manufactured in one process, whereby the manufacturing cost can be reduced, waste in material is not produced, and it is not necessary to dispose of metallic particles, because the bus bars are divided at the bridge portions without cutting away the same.
To these ends, according to an aspect of the present invention, an automotive lamp unit to be mounted in a vehicle comprises a plurality of bus bars embedded in a molded resin and used for switching on an automotive lamp. The plurality of bus bars formed integrally with each other via a bridge portion embedded in the molded resin are electrically separated from each other by being separated from each other at the bridge portion. The automotive lamp unit may be a passenger compartment lamp, a map lamp, a vanity-mirror lamp, a door lamp, or a trunk compartment lamp.
According to another aspect of the present invention, a method for manufacturing an automotive lamp unit to be mounted in a vehicle comprises the steps of preparing a plurality of bus bars formed integrally with each other via a bridge portion; setting the plurality of bus bars in an injection mold; electrically separating the plurality of bus bars by separating the same in the injection mold at the bridge portion; and embedding the plurality of bus bars in a molded resin by charging a resin into the injection mold.
The step of electrically separating the plurality of bus bars by separating the same in the injection mold at the bridge portion may include the step of cutting and raising the plurality of bus bars by a pin mounted on a fixed mold member of the injection mold. The bridge portion may be formed so as to have a reduced width, or may.be provided with a groove for cutting and raising thereat so that the bridge portion has a reduced thickness, thereby facilitating separation of the plurality of bus bars from each other.
The plurality of bus bars may be embedded in a molded resin by the injection mold, except for a lamp-holder member and a connector-terminal member of the plurality of bus bars. The plurality of bus bars having at least a lamp-holder member in a raised state may be set in the injection mold, and be embedded in a molded resin, except for a raised portion of the lamp holder member.